THE EMBRYOLOGY OF THE BIRD S LUNG 3 



features of his (M^lloidiu corrosion pi-cparations, however, is in a 

 note of exphmation of one of his figures in which he calls atten- 

 tion to a bronchial trunk larger than the others in the network 

 of air-tubes which extends to the dorsal surface of the lung on 

 its lateral side. This bronchial trunk, he says, 'directs itself 

 toward' the abdominal air-sac, but since it is the nature of re- 

 current bronchi to grow inward from the air-sacs, the language 

 employed by Fischer shows that he had a wrong conception of 

 these important structures. 



F. E. Schulze in 1909, '10 and '11 recognized these bronchi as 

 coming from the air-sacs and designated them both 'Riichljiu- 

 figen Bronchen' and 'Bronchi recurrentes sue Saccobronchi.' 

 With sketches he describes their origin from basal pockets on 

 the four posterior air-sacs, variations in the number of their 

 branches as well as the nature of their connections with para- 

 bronchi. His comparative observations embraced a variety of 

 birds including the chick, duck, goose, pigeon, Rhea, ostrich, 

 Cassowary, etc. In the Cassowary he noted that recurrent 

 bronchi are lacking on the abdominal air-sac. Schulze also points 

 out that the recurrent bronchi carry air from the air-sacs into the 

 lung parenchyma and play an important part in respiration. 



Juillet ('12) made an extensive study of the recurrent bronchi, 

 and since he was unacquainted with the observations of Schulze 

 he claims rank as the discoverer of the true anatomical relations 

 of these structures and of the part they play in the respiration of 

 birds. In all this however he was preceded by Schulze, and to a 

 limited extent he engaged in the study of the embryology of the 

 recurrent bronchi, which was not touched upon by Schulze. 



He found recurrent bronchi in all the twenty-four species of 

 birds which he examined. By a study of sections he traced some 

 stages of their development in the embryonic lungs of the chick, 

 and although he does not give an extended account of their de- 

 velopmental history, he arrived at a true conception of their ori- 

 gin and of their nature. 



No more important advance in the knowledge of the avian 

 lung has been made since William Harvey, in 1651, discovered 

 the perforations of the bronchi into the air-sacs and found them 



